Kurt von wysiecki



K. VON WYSIECKI SELF INDUCTION COIL Filed Nov. 28, 1925 5. Q y, Mm7///////////////A April 24, 1928.

embodiment of my invention for f rw rd. an r rn or ary conductors" withcrossed planesot wind- Patented Apr. 24, 1928.

UNITED STATES KURT VON WYSIECKI, 0F LAUSANN E, SWITZERLAND.

SELF-INDUCTION COIL.

Application filed November 28, 1925, Serial No. 71,9e4, and in GermanyAugust 18, 1924.

My invention relates to a self induction coilser'vingfor loading orpupinizing line circuits, the coil having an inner iron core and anouter iron casing. A constructional loading doublelin'e circuits may beobt'ainechior instance by arranging the windings for the primary andsecond- 1ng'i1ponacruciform ironcore the longitudinal windings being inthe sectors of the core, and such windings being" surrounded by acylindrical casing.

In the accompanying drawings which illustrate the preferred form of myinvention,

Figure 1 is ai'transverse section of a loading coil' without thewindings;

Figure 2 is a plan view of the core and wi dings, showing the samewithout the casing; 7

Figure Sillustrates a vertical longitudinal section of an end portion ofth'ecore, windings and the casing;

Figure 4 is a Vector diagram which shows schematically the magnetic,flux.

In the accompanying drawin s, 1 refers to a cruciform or cross-shapedcore, the arms thereof extending at right angles, and 2 refers to acylindrical outer casing, the internal diameter of the casing being inexcessof the length of the arms of the core.

- The rimar and secondar windin s l1 and 12 lie in the sector shapedspaces 3 and 4 formed by the arms and the casing and cross the ends ofthe core, asshown by Figs. 2 and 3 sotha t one winding will lie in twosectors or segmentally shaped spaces 3 and the other winding in the twosectors or segmental spaces 4, which spaces are between the arms of thecrucitorm'core.

The placing of the windings in the sectors or spaces between the arms ofthe core give rise to certain'symmetrical properties which are due tothe fact that the number of turns increases. approximatelyproportionally to the increasing radial distance from the centre of'thecore, as does also their average magnetic-motive action on the arm ofthe cross. This will be understood Without further explanation, if oneimagines that the action of each layer of wire is replaced by a singlewire'lying, 'tor example, onthe-line 5-5, through which a current ofn-times strength passes, where a is the number of wires in a layer inthe spaces between i I ing the number.

the arms of the core. The power vector of the symbol'n increases inproportion to the radial distance from the centre, "as does also theperpendicular distance of the corresponding wire on the line 5'-5 none;the arms of the cross on the two sides of the sector; The magneto-motiveforce in the cross is therefore of the same'majgnitude from pointtopoint. Consequently nostr ajy lines of magneticf't'orce can occur,*andthis results in the favourable electrical properties of the individualcoil or windings between opposite arms.

A similar consideration has been undertaken also for the outer casing,namely with respect to the individual sectors, on the supposition thatthe'magnetic fields when separately considered are simply superimposed.However, this undesirable property, namely that adjacent coils'stronglyinteract and it appears that when many coils were assembled in a box,where it'was necessary to fixthe coils in quite definite positions withrespect to one another so that the resulting magnetic fields of thecoils were at right angles and did not therefore disturb one another.This was a very di'ificult work and further some uncertainty and dangerof mutual disturbance always remained. v

According to my invention, it follows that for establishing the relativesizes of the magnetic flux on the one hand in the cross and on theotlienhand in the casing that the wires in the individual sectors must'not be taken into account, the total 'eitec't of all four sectors, asthis total .efi'ect on the cruciform core is quite different tromthatonthe casing. This can easily be illustrated if one imagines tha'tthetotaleflect produced by the wires in each sector is replaced, by a singlewire placed as it were in the electromagnetic centre through whi'ch aflux of m -t'old strength passes, m representof wires in the sector, asfor instance, in Fig. 1 the points 6, 7, 8, 9 represent these imaginarywires. It can be seen that at the point 19 in the core is a summation oftotal or aggregate efi'ect of the imaginary wires, forexample, at thepoint 10 in the casingthe vector or'forc'eetfect of 6 and 8 is oppositein direction. The'cruciform core and cylindrical casing in accordancewith my invention are of such dimensions with respect to oneanother thatthe ma netic resistance of the cross-shaped'core" 'is to that of thecylindrical "casingthe'Yunit Iii of the casing is as high length in thedirection of the lines of force, approximately as the resulting magneticforce of the four bundles of wires in the sectors between casing andcore. This mutual conformity can, when the casing and cross are made ofthe same material, be effected by suitable measurements of theircross-section. It is more advantageous however, to regard the size, andweight of the coil and to employ magnetic bodies with differentpermeability for the tubular casing and core, in which case thepermeability as possible and that of the cross-shaped core is lower.

The Working principle of the new self induction coil becomes more clearin detail from the magnetic vector diagram or figure shown in Fig. i.Wherein an electric current passes through the crossed windings 11, 12shown in Figs. 2 and 3, and if these windings 11, 12 are surrounded onlyby air as by removing the iron core 1 and the casing 2 there will beformed in a middle cross-section a magnetic field of lines of forceaccording to Fig. 4 in which 11 and 12 indicate schematically the crosssection of the one half of the crossed winding, 0 being the potential'lines and 7c the magnetic tubes of force. 2 re fers to the inner hollowspace of the casing serving for receiving the iron core 1. It is to benoted that, in consequence of the particular symmetrical properties ofthe cross winding, a magnetic field exists in the second arm of the core1 only when the directlOn of the electric current is reversed in the onepart of the windin and this is the case,

when pupinizing or l dading the combined line circuits by means of suchcoils, for the current in the phantom circuit in respect to the currentof the basic circuit. By considering the action only of one direction ofcurrent, a magnetic figure or diagram as shown in Fig. 4 is obtained.

As it is clear from Fig. 1, a considerably stronger resulting magnet1cflux exists in .the core than in the outer environs of the winding,because a summation of the-magnetomotive vectors of the four bundles ofwires in the sectors 3 and t-see Fig. 1- takes place in the inner spaceof the coil, whilst in the outer environs of the coil a subtraction ofthese magnetoinotive vectors occurs. Consequently, the magnetic flux ishigher or compressed in the interior of the core, and is enabled toexpand freely on the outside. In the vector diagram Fig. ithe first tubeof force on theoutside of the winding in the point 17 has, for instance,approximately the same cross-section as the eight tubes of force in theinner space 16 of the winding. 1

Ifiron bodies of the same permeability are employed for core and casingand if the casing has a form corresponding to the tube of force with themaximum cross-section 17, the outer casing will receive in itself, as itbecomes clear from Fig. l, only'about a uarter of all the lines of forceleaving the core; Such a coil will be, therefore, absolutely useless,because it has very great electrical losses in consequence of thisstray, and furthermore such coils will mutually interact even whensituated at a very large distant one from the other.

it is to have in mind that the magnetic flux fiow on both sides ofthecoilaround the winding, so that theftotal flux leaving the core isdivided in two portions.

By providing a casing having a cross-section equal to that of themagnetic tube of force at the point 17, Fig. 4, where the magnetomotivevector is, for instance, eight times smaller than in the inner space 16vof the coil, the magnetic resistance of the casing should be about fourtimes smaller than the magnetic resistance of the core. In the caseofthis example, the 0011 will be provided wlth a casing and a core ofdlf- 'it'erent material as to permeability the casing having apermeability about four times higher than that ofthe core. Then, the airgap between core and casing can be considerably smaller and serves in acertain manner only for exactly and sensibly adjusting the mag neticresistances of the casing and the core in conformity with the vectors ofE. M. F.

revailing at that place.

When providing core and casing and making the core and the casing of thesame material, a favourable result can be obtained by conforming thecross-section of the casing in a suitable manner to the magneticresistance of the cross shaped core including the air gap. In this wayit is possible, as thepractice hasproved, to avoid the inconvenience ofthe cross-talk incident to the Pupin coils as previously constructed.

From the foregoing it will be noted that only the portions of eachwinding lying between the spaces of the cruciform core have receivedconsideration, but not the connecting parts of each and below the core.These wires'are afurther cause of the above mentioned disturbance ofneighboring coils. The upper Wires of the two crossing windings areillustrated diagrammatically in plan by Fig one winding is representedby and the other by the lines 12.

A resultant 2. The the lines 11' a large air gap between winding whichpass above I magnetic flux according to the direction of flow ofelectric current in each is produced in the direction of the axes 1313and 1llet shown on Fig 2. This flux passes between the cross arms andthe windings out of the interior of the coil and is collected accordingto my invention, as shown in Fig. 3, by an extension 15 of the casing 2at each end of the casing. The ring-shaped extension 15 must howeveralso conform exactly to the conditions in respect of its magneticsusceptibility so that the density of the lines of force in it, when itis taking up all the stray lines of force of the end wires, is the sameas the density of the lines of force in the casing. If this be not thecase, lines of force overflow from the core and casing into it whichgives rise to a considerable increase in the resistance losses of thecoil. The adjustment may be facilitated by insulating the extension fromthe remainder of the casing by means of an intermediate layer ofnon-magnetic material.

By means of the precautions in accord ance with the invention the resultis obtained that not only are the above mentioned constructionaldifiiculties and disturbances entirely avoided, but the electricalproperties of the coil also are considerably more favourable, especiallythe dependency of the losses on the strength of current and frequency.Furthermore the principle of my invention can be employed not only inthe case of coils having a cruciform iron core but also for coils theiron core of which is not cruciform, the principle consisting in thatthe stray lines are drawn into the casing by conforming the magneticresistance of core and casing to the power flux produced by the windingsin longitudinal spaces between the arms of the core.

I claim:

1. A loading coil comprising a core of ferromagnetic material having ashape which is elongated and cruciform in cross section, a casing offerromagnetic material surrounding the core, windings crossing eachother at right angles on the ends of the core and passing throughopposite sectors formed by the arms of the core and by the casing, themagnetic resistances of core and easing being proportional to the powerflux produced by the windings at the places of core and casing.

2. A loading coil comprising an inner core of ferromagnetic materialhaving a shape which is elongated and cruciform in cross section, acasing of ferromagnetic material surounding the core, windings crossingeach other at right angles on the ends of the core and passing throughopposite sectors formed by the arms of the core and by the casing, themagnetic resistances of these bodies being adapted proportionally to thepower vectors produced by the windings in air alone at the places ofcore and casing when core and casing being omitted.

3. A loading coil comprising a core of ferromagnetic material having ashape which is elongated and cruciform in cross section, a casing offerromagnetic material surrounding the core, windings crossing eachother at right angles on the ends of the core and passing throughopposite sectors formed by the arms of the core and by the casing, themagnetic resistances of core and easing being proportional to the powerflux produced by the windings at the places of core and casing, thecasing carrying at each end a ring-shaped extension insulated from thecasing for taking up the power flux produced at the crossing of thewindings.

4t. A loading coil comprising an inner core of ferromagnetic materialhaving a. shape which is elongated and cruciform in cross section, acasing of ferromagnetic material surrounding the core, windings crossingeach other at right angles on the ends of the core and passing throughopposite sectors formed by the arms of the core and by the casing, themagnetic resistances of core and casing being made proportional to theflux vector produced by the windings at the places of core and casing byproviding air gaps in the draught of the core.

5. A loading coil comprising an inner core of ferromagnetic material andof a shape elongated and cruciform in cross-section, a casing offerromagnetic material surrounding the core and having an inner diametergreater than the length of the arms of the core, windings passingthrough the sectors between the arms of the core and the casing andcrossing each other on the ends of the core, the magnetic resistances ofcore and casing being in proportion to the flux produced by thewindings.

In testimony whereof I allix my signature.

KURT VON VVYSIECKI.

